1. Field of the Invention
The present invention relates generally to devices used for lifting objects on to a roof structure and, more particularly, to devices for preventing objects lifted towards a roof by an individual from becoming entangled with an under or lower portion of the roof structure.
2. Background of the Prior Art
Professional persons involved in the heating, ventilating and air-conditioning (HVAC) business, and also in the roofing industry as well as non-professionals for various reasons often need to lift equipment or materials to the roof of a building. Although heavy machinery, such as cranes with an attached cherry picker, hoists and booms can perform the task, the time and expense of transporting the machinery to the desired location makes it impracticable. Generally, personnel must use either a pick-up truck or a van to transport their equipment and materials. In other cases, it is not practical to use heavy machinery due to accessibility problems. As a result, easily lifting objects such as compressors, motors, shingles, boxes nails, tools, or other materials to a roof by carpenters, roofers, maintenance technicians, or other repairmen without damaging the exterior of a building, the lifted object or the lifters back has been a problem for decades.
Although prior art devices exist to lift objects to the roof of a building, an exhaustive method often used is to manually lift the objects along a ladder from the ground to the roof to prevent damage to the exterior of the building and to the lifted object This is especially true when the repairman is using his own equipment.
Several devices have been introduced for raising objects along a building's exterior. For example, U.S. Pat. No. 3,860,092 provides an overhead support for hoisting a rope which can enable the user to lift objects along the exterior surface of a building. The device is designed primarily for emergency situations involving the fighting of fires. As such, the device has certain disadvantages when adapted to lift equipment or tools for repairs or servicing. First, the repairman's vehicle must have a winch attached to it for coupling with one end of the load line and a power supply to operate the winch. This can be impracticable using small vehicles. Second, the equipment or material lifted can slide against the building's exterior causing harm to the equipment, material, or exterior of the building while in use. Although this is acceptable in an emergency, it is unacceptable in a non-emergency. Furthermore, lifted objects can become stuck under the building's soffit, increasing the difficulty to raise the objects to the roof and causing further damage. Third, the object is generally raised a distance away from the roof of the building creating a dangerous situation whereby the repairman has to extend himself beyond the edge of the roof to retrieve the object. Additionally, the object when fully raised is below the level of the roof making retrieval of the object even more difficult and dangerous. Finally, the device requires existing building structures on the roof and ground to be free of defects.
Similar problems exist for U.S. Pat. No. 4,402,489 which discloses a protective hoisting guide over the edge of a roof The hoisting guide is designed to protect the rope from breaking. Equipment, materials, and the building are not protected as objects slide along the building's exterior. Retrieval of the object is again below the surface of the roof at the end of the hoisting guide, and can be complicated due to the building's soffit.
Another device for raising or lowering materials is U.S. Pat. No. 5,341,898 having an overhead support for hoisting a rope. Again, this device was designed for emergency situations involving safety and rescue. The device is complex, costly and difficult to set-up. Further, the device raises an object away from the edge of the roof increasing the difficulty of retrieving it. Also, for larger objects, there is no protection for either the building's exterior or the lifted object. Finally, objects can engage and damage the soffit.
A need exists in the art for an inexpensive, quick set-up, portable device whereby an object can be readily lifted to the roof of a building without damaging either the object or the building, and providing safety and avoiding injury of the individual lifting the object. Additionally, the device should allow for easy retrieval of the object without extension beyond the edge of the building's roof. It is also highly desirable that such a device be easily removed from the roof and easily transported and that it be adaptable to various roof structures.